Sympathetic control of plasma levels of free fatty acids and triglycerides in pygmy goats

Abstract

The aim of the present study was to determine the relevance of α 1-, α 2- and β-adrenergic receptors in controlling plasma free fatty acids (FFA) and triglyceride (TG) levels in pygmy goats in the absence of severe stress. Twelve adult female pygmy goats were used. The animals were housed in single cages. Adrenergic drugs or vehicle were injected intraperitoneally in counterbalanced order, and blood samples were taken by puncture of the jugular vein. Due to the cross-over design of the experiments each animal served as its own control. Blockade of α-adrenergic receptors by phentolamine ( α 1- and α 2-adrenergic antagonist) or prazosine ( α 1-adrenergic antagonist) increased ( P < 0.01) plasma FFA and decreased ( P < 0.05) plasma triglycerides. Blockade of β-adrenergic receptors by propranolol decreased ( P < 0.01) plasma FFA, but had no significant effect on plasma TG. The α 2-adrenergic antagonist yohimbine increased ( P < 0.01) plasma FFA and had no effect on plasma TG. The ganglion blocking agent hexamethonium elicited a decrease ( P < 0.01) in plasma FFA and plasma TG. The α 1-adrenergic agonist xylometazolin increased ( P < 0.01) plasma TG without affecting plasma FFA. From these findings it is concluded, that the sympathetic nervous system may play an important role in control of plasma lipids in pygmy goats and perhaps other ruminants in the absence of severe stress.